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ftpd(8)

NAME

     ftpd -- Internet File Transfer Protocol server

SYNOPSIS

     ftpd [-46ADdEhMmOoRrSUvW] [-l [-l]] [-a address] [-P port] [-p file]
	  [-T maxtimeout] [-t timeout] [-u umask]

DESCRIPTION

     The ftpd utility is the Internet File Transfer Protocol server process.
     The server uses the TCP protocol and listens at the port specified with
     the -P option or in the ``ftp'' service specification; see services(5).

     Available options:

     -4      When -D is specified, accept connections via AF_INET socket.

     -6      When -D is specified, accept connections via AF_INET6 socket.

     -A      Allow only anonymous ftp access.

     -a      When -D is specified, accept connections only on the specified
	     address.

     -D      With this option set, ftpd will detach and become a daemon,
	     accepting connections on the FTP port and forking children pro-
	     cesses to handle them.  This is lower overhead than starting ftpd
	     from inetd(8) and is thus useful on busy servers to reduce load.

     -d      Debugging information is written to the syslog using LOG_FTP.

     -E      Disable the EPSV command.	This is useful for servers behind
	     older firewalls.

     -h      Disable printing host-specific information, such as the server
	     software version or hostname, in server messages.

     -l      Each successful and failed ftp(1) session is logged using syslog
	     with a facility of LOG_FTP.  If this option is specified twice,
	     the retrieve (get), store (put), append, delete, make directory,
	     remove directory and rename operations and their filename argu-
	     ments are also logged.  By default, syslogd(8) logs these to
	     /var/log/xferlog.

     -M      Prevent anonymous users from creating directories.

     -m      Permit anonymous users to overwrite or modify existing files if
	     allowed by file system permissions.  By default, anonymous users
	     cannot modify existing files; in particular, files to upload will
	     be created under a unique name.

     -O      Put server in write-only mode for anonymous users only.  RETR is
	     disabled for anonymous users, preventing anonymous downloads.
	     This has no effect if -o is also specified.

     -o      Put server in write-only mode.  RETR is disabled, preventing
	     downloads.

	     tions on PORT requests.  Currently, ftpd will only honor PORT
	     commands directed to unprivileged ports on the remote user's host
	     (which violates the FTP protocol specification but closes some
	     security holes).

     -r      Put server in read-only mode.  All commands which may modify the
	     local file system are disabled.

     -S      With this option set, ftpd logs all anonymous file downloads to
	     the file /var/log/ftpd when this file exists.

     -T      A client may also request a different timeout period; the maximum
	     period allowed may be set to timeout seconds with the -T option.
	     The default limit is 2 hours.

     -t      The inactivity timeout period is set to timeout seconds (the
	     default is 15 minutes).

     -U      This option instructs ftpd to use data ports in the range of
	     IP_PORTRANGE_DEFAULT instead of in the range of
	     IP_PORTRANGE_HIGH.  Such a change may be useful for some specific
	     firewall configurations; see ip(4) for more information.

	     Note that option is a virtual no-op in FreeBSD 5.0 and above;
	     both port ranges are indentical by default.

     -u      The default file creation mode mask is set to umask, which is
	     expected to be an octal numeric value.  Refer to umask(2) for
	     details.  This option may be overridden by login.conf(5).

     -v      A synonym for -d.

     -W      Do not log FTP sessions to /var/log/wtmp.

     The file /var/run/nologin can be used to disable ftp access.  If the file
     exists, ftpd displays it and exits.  If the file /etc/ftpwelcome exists,
     ftpd prints it before issuing the ``ready'' message.  If the file
     /etc/ftpmotd exists, ftpd prints it after a successful login.  Note the
     motd file used is the one relative to the login environment.  This means
     the one in ~ftp/etc in the anonymous user's case.

     The ftp server currently supports the following ftp requests.  The case
     of the requests is ignored.  Requests marked [RW] are disabled if -r is
     specified.

	   Request    Description
	   ABOR       abort previous command
	   ACCT       specify account (ignored)
	   ALLO       allocate storage (vacuously)
	   APPE       append to a file [RW]
	   CDUP       change to parent of current working directory
	   CWD	      change working directory
	   DELE       delete a file [RW]
	   EPRT       specify data connection port, multiprotocol
	   EPSV       prepare for server-to-server transfer, multiprotocol
	   HELP       give help information
	   LIST       give list files in a directory (``ls -lgA'')
	   LPRT       specify data connection port, multiprotocol
	   PORT       specify data connection port
	   PWD	      print the current working directory
	   QUIT       terminate session
	   REST       restart incomplete transfer
	   RETR       retrieve a file
	   RMD	      remove a directory [RW]
	   RNFR       specify rename-from file name [RW]
	   RNTO       specify rename-to file name [RW]
	   SITE       non-standard commands (see next section)
	   SIZE       return size of file
	   STAT       return status of server
	   STOR       store a file [RW]
	   STOU       store a file with a unique name [RW]
	   STRU       specify data transfer structure
	   SYST       show operating system type of server system
	   TYPE       specify data transfer type
	   USER       specify user name
	   XCUP       change to parent of current working directory
		      (deprecated)
	   XCWD       change working directory (deprecated)
	   XMKD       make a directory (deprecated) [RW]
	   XPWD       print the current working directory (deprecated)
	   XRMD       remove a directory (deprecated) [RW]

     The following non-standard or UNIX specific commands are supported by the
     SITE request.

	   Request    Description
	   UMASK      change umask, e.g. ``SITE UMASK 002''
	   IDLE       set idle-timer, e.g. ``SITE IDLE 60''
	   CHMOD      change mode of a file [RW], e.g. ``SITE CHMOD 755
		      filename''
	   MD5	      report the files MD5 checksum, e.g. ``SITE MD5
		      filename''
	   HELP       give help information

     Note: SITE requests are disabled in case of anonymous logins.

     The remaining ftp requests specified in Internet RFC 959 are recognized,
     but not implemented.  MDTM and SIZE are not specified in RFC 959, but
     will appear in the next updated FTP RFC.  To avoid possible denial-of-
     service attacks, SIZE requests against files larger than 10240 bytes will
     be denied if the current transfer type is ASCII.

     The ftp server will abort an active file transfer only when the ABOR com-
     mand is preceded by a Telnet "Interrupt Process" (IP) signal and a Telnet
     "Synch" signal in the command Telnet stream, as described in Internet RFC
     959.  If a STAT command is received during a data transfer, preceded by a
     Telnet IP and Synch, transfer status will be returned.

     The ftpd utility interprets file names according to the ``globbing'' con-
     ventions used by csh(1).  This allows users to utilize the metacharacters
     ``*?[]{}~''.

     The ftpd utility authenticates users according to six rules.

	   1.	The login name must be in the password data base and not have
		a null password.  In this case a password must be provided by
		Bellcore.

	   2.	The login name must not appear in the file /etc/ftpusers.

	   3.	The login name must not be a member of a group specified in
		the file /etc/ftpusers.  Entries in this file interpreted as
		group names are prefixed by an "at" `@' sign.

	   4.	The user must have a standard shell returned by
		getusershell(3).

	   5.	If the user name appears in the file /etc/ftpchroot, or the
		user is a member of a group with a group entry in this file,
		i.e., one prefixed with `@', the session's root will be
		changed to the directory specified in this file or to the
		user's login directory by chroot(2) as for an ``anonymous'' or
		``ftp'' account (see next item).  See ftpchroot(5) for a
		detailed description of the format of this file.  This facil-
		ity may also be triggered by enabling the boolean "ftp-chroot"
		capability in login.conf(5).  However, the user must still
		supply a password.  This feature is intended as a compromise
		between a fully anonymous account and a fully privileged
		account.  The account should also be set up as for an anony-
		mous account.

	   6.	If the user name is ``anonymous'' or ``ftp'', an anonymous ftp
		account must be present in the password file (user ``ftp'').
		In this case the user is allowed to log in by specifying any
		password (by convention an email address for the user should
		be used as the password).  When the -S option is set, all
		transfers are logged as well.

     In the last case, ftpd takes special measures to restrict the client's
     access privileges.  The server performs a chroot(2) to the home directory
     of the ``ftp'' user.  As a special case if the ``ftp'' user's home direc-
     tory pathname contains the /./ separator, ftpd uses its left-hand side as
     the name of the directory to do chroot(2) to, and its right-hand side to
     change the current directory to afterwards.  A typical example for this
     case would be /usr/local/ftp/./pub.  In order that system security is not
     breached, it is recommended that the ``ftp'' subtree be constructed with
     care, following these rules:

	   ~ftp      Make the home directory owned by ``root'' and unwritable
		     by anyone.

	   ~ftp/etc  Make this directory owned by ``root'' and unwritable by
		     anyone (mode 555).  The files pwd.db (see passwd(5)) and
		     group(5) must be present for the ls(1) command to be able
		     to produce owner names rather than numbers.  The password
		     field in passwd(5) is not used, and should not contain
		     real passwords.  The file ftpmotd, if present, will be
		     printed after a successful login.	These files should be
		     mode 444.

	   ~ftp/pub  This directory and the subdirectories beneath it should
		     be owned by the users and groups responsible for placing
		     files in them, and be writable only by them (mode 755 or
		     775).  They should not be owned or writable by ``ftp'' or

     fields separated by whitespace:

	   hostname  Contains the hostname or IP address of the virtual host.

	   user      Contains a user record in the system password file.  As
		     with normal anonymous ftp, this user's access uid, gid
		     and group memberships determine file access to the anony-
		     mous ftp area.  The anonymous ftp area (to which any user
		     is chrooted on login) is determined by the home directory
		     defined for the account.  User id and group for any ftp
		     account may be the same as for the standard ftp user.

	   statfile  File to which all file transfers are logged, which
		     defaults to /var/log/ftpd.

	   welcome   This file is the welcome message displayed before the
		     server ready prompt.  It defaults to /etc/ftpwelcome.

	   motd      This file is displayed after the user logs in.  It
		     defaults to /etc/ftpmotd.

     Lines beginning with a '#' are ignored and can be used to include com-
     ments.

     Defining a virtual host for the primary IP address or hostname changes
     the default for ftp logins to that address.  The 'user', 'statfile',
     'welcome' and 'motd' fields may be left blank, or a single hyphen '-'
     used to indicate that the default value is to be used.

     As with any anonymous login configuration, due care must be given to set-
     up and maintenance to guard against security related problems.

     The ftpd utility has internal support for handling remote requests to
     list files, and will not execute /bin/ls in either a chrooted or non-
     chrooted environment.  The ~/bin/ls executable need not be placed into
     the chrooted tree, nor need the ~/bin directory exist.

FILES

     /etc/ftpusers     List of unwelcome/restricted users.
     /etc/ftpchroot    List of normal users who should be chroot'd.
     /etc/ftphosts     Virtual hosting configuration file.
     /etc/ftpwelcome   Welcome notice.
     /etc/ftpmotd      Welcome notice after login.
     /var/run/nologin  Displayed and access refused.
     /var/log/ftpd     Log file for anonymous transfers.
     /var/log/xferlog  Default place for session logs.

SEE ALSO

     ftp(1), key(1), umask(2), getusershell(3), ftpchroot(5), login.conf(5),
     inetd(8), syslogd(8)

HISTORY

     The ftpd utility appeared in 4.2BSD.  IPv6 support was added in WIDE
     Hydrangea IPv6 stack kit.

BUGS

     The server must run as the super-user to create sockets with privileged
     port numbers.  It maintains an effective user id of the logged in user,

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